This application pertains to the art of electronic anti-theft devices. The invention finds particular application in vehicular and automotive anti-theft systems and will be described with particular reference thereto. However, the invention also finds application in other arts where it is desirable to limit access to a structure or area, such as residential or hotel door keys, pass keys for higher security rooms or tools, or the like.
Heretofore, automotive anti-theft systems have commonly included a passenger compartment located digital keyboard or electronic key for enabling the vehicle's ignition to be operated, note for example U.S. Pat. No. 4,192,400, issued Mar. 11, 1980 to J. A. McEwan. However, ignition enabling devices located inside the car do not protect the contents of the car or the vehicle itself from unauthorized entry or vandalism.
To protect the vehicle and its contents from unauthorized entry, automotive anti-theft device systems have been developed in which a key is mounted in the fender of the vehicle for actuating and deactuating an alarm or an ignition control device. The alarm is commonly connected to the vehicle's doors such that opening the door while the alarm device is enabled actuates the alarm. However, the mechanical key switches mounted in the vehicle's fender are often easier to pick than the vehicle's original equipment door locks. Further the mechanical lock switches are readily pulled from the fender and hot wired to disable the alarm. Another problem with the fender mounted mechanial key switch is that the operator must enable the alarm with the key. Frequently, the operator forgets or does not both to enable the alarm system. Accordingly, many insurance companies will accord no discount in auto rates unless the alarm system is self-arming, commonly known as, a "passive" anti-theft system.
In other prior art automotive anti-theft systems, the alarm system is actuated automatically when the ignition is turned off or the vehicle is exitted. This type of system is commonly known as a "passive" alarm system. Commonly, turning off the ignition or exiting the vehicle starts a delay timer operating which enables the alarm system after a predetermined delay. When the authorized operator returns to the vehicle and opens the door, the delay timer again provides the predetermined delay before the alarm is set off. This delay accords the authorized operator time to enter a preselected code into a digital keyboard or the like. One problem with this type of alarm is that it provides only limited protection for the contents of the vehicle. The re-entry delay before the alarm is set off, generally about thirty seconds, also accords a thief sufficient time to remove packages or electronic equipment and leave the area before the alarm sounds.
The present invention contemplates a new and improved anti-theft system which overcomes the above-referenced problems and others.